I bought 8 Thunder Power 6s 7700 65C lipos about four months ago. I have finally finished the plane they are going in and am now charging them (kept at storage charge up until now). The packs will be used in series for 12s.

I noticed that one 6s pack has much higher resistence, 8 to 10 times higher, than the other packs. In addition to high resistence, my charger has a very hard time balancing this pack.

I have tried using different charging cables, different ports on my charger, two different chargers, I get the same result.

Has anyone encountered this problem before, and is there anything I can do other than return the pack to Thunder Power?